Ivan Rogers PA PA Wire/PA Images LONDON — Britain's Brexit negotiations will take up to a decade and be on a "humongous scale" the like of which has not been seen since the last World War, EU officials have told the UK.

Former ambassador to the UK, Sir Ivan Rogers, told MPs that he had not spoken to a single senior EU official who believed that negotiations could be completed in time for Britain's exit from the EU in 2019.

"The consensus wisdom among the technocracy around Brussels... is that Free Trade Agreements take a long time and with the best will in the world, it will not culminate by 2018," Rogers said.

"My summary of the senior beltway wisdom of the people I spoke to on a daily basis was that it would probably take until the early to mid-2020s for ratification."

"I have not found a single senior person in any of those organs who has diverged from that view."

Rogers pointed to previous EU free trade negotiations which have taken up to seven years to complete and dismissed those who claimed it could be wrapped up in just two years.

"You do not, with the EU, negotiate something of that length and gravity in that length of time," he said.

Britain is also set to be hit by a huge exit bill of around forty to sixty billion euros, EU officials told Rogers.

He told the European Scrutiny Committee that the consensus view in Brussels is that the UK would accept their demands due to the short two-year process allowed for negotiations under Article 50.

"I think the view from many will be that the implications for the UK of walking away without any deal on the economic side.. and walking into a WTO world, from their perspective [would] be so unpalatable that we won't do it."

"And that will oblige us to consider transitional arrangements which will bridge us to that deal".

He warned that negotiations would be intensely fractious and would descend into "name-calling and fist-fighting".

Rogers resigned as EU ambassador earlier this year after it was made clear by Theresa May's government that they had lost confidence in his "pessimistic" view of Brexit.

In his resignation letter, Rogers urged his colleagues to take on the "muddled thinking" and "ill-founded arguments" of those in power.

"I hope you will continue to challenge ill-founded arguments and muddled thinking and that you will never be afraid to speak the truth to those in power," he wrote.

"I hope that you will support each other in those difficult moments where you have to deliver messages that are disagreeable to those who need to hear them."

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